N-(substituted glycyl)-pyrrolidines, pharmaceutical compositions containing them and their use in inhibiting dipeptidyl peptidase-IV

ABSTRACT

The invention discloses certain N-(substituted glycyl)-pyrrolidines, pharmaceutical compositions containing said compounds as an active ingredient thereof, and the use of said compounds in inhibiting dipeptidyl peptidase-IV.

This application claims the benefit of U.S. Provisional Application No.60/146,183, filed Jul. 29, 1999.

FIELD OF THE INVENTION

The present invention relates to the area of dipeptidyl peptidase-IVinhibition and, more particularly, relates to certain N-(substitutedglycyl)-pyrrolidines, pharmaceutical compositions containing saidcompounds, and the use of said compounds in inhibiting dipeptidylpeptidase-IV.

BACKGROUND OF THE INVENTION

Dipeptidyl peptidase-IV (DPP-IV) is a serine protease which cleavesN-terminal dipeptides from a peptide chain containing, preferably, aproline residue in the penultimate position. Although the biologicalrole of DPP-IV in mammalian systems has not been completely established,it is believed to play an important role in neuropeptide metabolism,T-cell activation, attachment of cancer cells to the endothelium and theentry of HIV into lymphoid cells.

More recently, it was discovered that DPP-IV is responsible forinactivating glucagon-like peptide-1 (GLP-1). More particularly, DPP-IVcleaves the amino-terminal His-Ala dipeptide of GLP-1, generating aGLP-1 receptor antagonist, and thereby shortens the physiologicalresponse to GLP-1. Since the half-line for DPP-IV cleavage is muchshorter than the half-life for removal of GLP-1 from circulation, asignificant increase in GLP-1 bioactivity (5- to 10-fold) is anticipatedfrom DPP-IV inhibition. Since GLP-1 is a major stimulator of pancreaticinsulin secretion and has direct beneficial effects on glucose disposal,DPP-IV inhibition appears to represent an attractive approach fortreating non-insulin-dependent diabetes mellitus (NIDDM).

Although a number of DPP-IV inhibitors have been described in theliterature, all have limitations relating to potency, stability ortoxicity. Accordingly, it is clear that a great need exists for novelDPP-IV inhibitors which are useful in treating conditions mediated byDPP-IV inhibition and which do not suffer from the above-mentionedlimitations of known DPP-IV inhibitors.

DESCRIPTION OF THE PRIOR ART

WO 95/15309 discloses certain peptide derivatives which are inhibitorsof DPP-IV and, therefore, are useful in treating a number of DPP-IVmediated processes.

WO 95/13069 discloses certain cyclic amine compounds which are useful instimulating the release of natural or endogenous growth hormone.

European Patent 555,824 discloses certain benzimidazolyl compounds whichprolong thrombin time and inhibit thrombin and serine-related proteases.

Archives of Biochemistry and Biophysics, Vol. 323, No. 1, pgs. 148-154(1995) discloses certain aminoacylpyrrolidine-2-nitriles which areuseful as DPP-IV inhibitors.

Journal of Neurochemistry, Vol. 66, pgs. 2105-2112 (1996) disclosescertain Fmoc-aminoacylpyrrolidine-2-nitriles which are useful ininhibiting prolyl oligopeptidase.

Bulletin of the Chemical Society of Japan, Vol. 50, No. 7, pgs.1827-1830 (1977) discloses the synthesis of an aminohexapeptide, viz.,Z-Val-Val-lmPro-Gly-Phe-Phe-OMe, and its related aminopeptides. Inaddition, the antimicrobial properties of said compounds were examined.

Bulletin of the Chemical Society of Japan, Vol. 51, No. 3, pgs. 878-883(1978) discloses the synthesis of two known peptide antibiotics, viz.,Bottromycins B₁ and B₂ according to the structures proposed by Nakamura,et al. However, since the resultant compounds were devoid ofantimicrobial properties, it was concluded that the structures proposedby Nakamura, et al. were erroneous.

WO 90/12005 discloses certain amino acid compounds which inhibitprolylendopeptidase activity and, therefore, are useful in treatingdementia or amnesia.

Derwent Abstract 95: 302548 discloses certain N-(aryl(alkyl)carbonyl)substituted heterocyclic compounds which are cholinesterase activatorswith enhanced peripheral selectivity useful in treating conditions dueto the lowering of cholinesterase activity.

Chemical Abstracts 84: 177689 discloses certain1-acyl-pyrrolidine-2-carbonitrile compounds which are useful asintermediates for proline compounds exhibiting angiotensin convertingenzyme (ACE) inhibiting activity.

Chemical Abstracts 96: 116353 discloses certain3-amino-2-mercapto-propyl-proline compounds which are Rasfarnesyl-transferase inhibitors useful in treating various carcinomas ormyeloid leukemias.

WO 95/34538 discloses certain pyrrolidides, phosphonates, azetidines,peptides and azaprolines which inhibit DPP-IV and, therefore, are usefulin treating conditions mediated by DPP-IV inhibition.

WO 95/29190 discloses certain compounds characterized by a plurality ofKPR-type repeat patterns carried by a peptide matrix enabling theirmultiple presentation to, and having an affinity for, the enzyme DPP-IV,which compounds exhibit the ability to inhibit the entry of HIV intocells.

WO 91/16339 discloses certain tetrapeptide boronic acids which areDPP-IV inhibitors useful in treating autoimmune diseases and conditionsmediated by IL-2 suppression.

WO 93/08259 discloses certain polypeptide boronic acids which are DPP-IVinhibitors useful in treating autoimmune diseases and conditionsmediated by IL-2 suppression.

WO 95/11689 discloses certain tetrapeptide boronic acids which areDPP-IV inhibitors useful in blocking the entry of HIV into cells.

East German Patent 158109 discloses certain N-protectedpeptidyl-hydroxamic acids and nitrobenzoyloxamides which are useful as,inter alia, DPP-IV inhibitors.

WO 95/29691 discloses, inter alia, certain dipeptide prolinephosphonates which are DPP-IV inhibitors useful in the treatment ofimmune system disorders.

German Patent DD 296075 discloses certain amino acid amides whichinhibit DPP-IV.

Biochimica et Biophysica Acta, Vol. 1293, pgs. 147-153 discloses thepreparation of certain di- and tri-peptide p-nitroanilides to study theinfluence of side chain modifications on their DPP-IV and PEP-catalyzedhydrolysis.

Bioorganic and Medicinal Chemistry Letters, Vol. 6, No. 10, pgs.1163-1166 (1996) discloses certain 2-cyanopyrrolidines which areinhibitors DPP-IV.

J. Med. Chem., Vol. 39, pgs. 2087-2094 (1996) discloses certainprolineboronic acid-containing dipeptides which are inhibitors ofDPP-IV.

Diabetes, Vol. 44, pgs. 1126-1131 (September '96) is directed to a studywhich demonstrates that GLP-I amide is rapidly degraded whenadministered by subcutaneous or intravenous routes to diabetic andnon-diabetic subjects.

SUMMARY OF THE INVENTION

The present invention provides new DPP-IV inhibitors which are effectivein treating conditions mediated by DPP-IV inhibition. More particularly,the present invention relates to certain N-(substitutedglycyl)-pyrrolidines which inhibit DPP-IV. In addition, the presentinvention provides pharmaceutical compositions useful in inhibitingDPP-IV comprising a therapeutically effective amount of a certainN-(substituted glycyl)-pyrrolidine. Moreover, the present inventionprovides a method of inhibiting DPP-IV comprising administering to amammal in need of such treatment a therapeutically effective amount of acertain N-(substituted glycyl)-pyrrolidine.

DETAILED DESCRIPTION OF THE INVENTION

The essence of the instant invention is the discovery that certainN-(substituted glycyl)-pyrrolidines are useful in inhibiting DPP-IV. Inone embodiment, the present invention provides compounds of formula I:

wherein R is a group

an unsubstituted (C₃₋₇)-cycloalkyl ring; a (C₃₋₇)cycloalkyl ringsubstituted in the 1-position by a hydroxy(C₁₋₃)alkyl group; a groupCH₂₂R₂; a group

 a group CH₂₃R₄; an isopropyl group; or an isopropyl group substitutedin the 1-position by a hydroxy(C₁₋₃)alkyl group;

R₁ is an unsubstituted pyridine ring; a pyridine ring mono- ordi-substituted by halo, trifluoromethyl, cyano or nitro; anunsubstituted pyrimidine ring; or a pyrimidine ring monosubstituted byhalo, trifluoromethyl, cyano or nitro;

R₂ is an unsubstituted phenyl ring; or a phenyl ring mono-, di- ortri-substituted by halo or (C₁₋₃)alkoxy;

each R_(3,) independently, is an unsubstituted phenyl ring; or a phenylring mono-substituted by halo or (C₁₋₃)alkoxy; and

R₄ is a 2-oxopyrrolidine group or a (C₂₋₄)alkoxy group;

or a pharmaceutically acceptable acid addition salt thereof.

Preferred compounds are those of formula Ia:

where R′ is a group CH₂₂N—R′₁; an unsubstituted (C₃₋₇)cycloalkyl ring;a (C₃₋₇) cycloalkyl ring substituted in the 1-position by ahydroxy(C₁₋₃)alkyl group; or a group CH₂₃R′₄;

R′₁ is an unsubstituted pyridine ring; a pyridine ring mono- ordi-substituted by halo, trifluoromethyl, cyano or nitro; or anunsubstituted pyrimidine ring; and

R′₄ is a (C₂₋₄)alkoxy group;

or a pharmaceutically acceptable acid addition salt thereof.

More preferred compounds are those of formula Ib:

where R″ is a group CH₂₂N—R″₁; a (C₄₋₆)cycloalkyl ring substituted inthe 1-position by a hydroxy(C₁₋₃)alkyl group; or a group CH₂₃R′₄;

R″₁ is a pyridine ring mono- or di-substituted by halo, trifluoromethyl,cyano or nitro; and

R′₄ is as defined above;

or a pharmaceutically acceptable acid addition salt thereof.

Even more preferred compounds are those of formula Ic:

where R″′ is a group CH₂₂N—R″′₁; a (C₄₋₆)cycloalkyl ring substitutedin the 1-position by a hydroxymethyl group; or a group CH₂₃R′₄;

R″′ is a pyridine ring monosubstituted by halo, trifluoromethyl, cyanoor nitro; and

R′₄ is as defined above;

or a pharmaceutically acceptable acid addition salt thereof.

In another embodiment, the instant invention provides pharmaceuticalcompositions useful in inhibiting DPP-IV comprising a pharmaceuticallyacceptable carrier or diluent and a therapeutically effective amount ofa compound of formula I above, or a pharmaceutically acceptable acidaddition salt thereof, preferably a compound of formula Ia above, or apharmaceutically acceptable acid addition salt thereof, more preferablya compound of formula Ib above, or a pharmaceutically acceptable acidaddition salt thereof, and even more preferably a compound of formula Icabove, or a pharmaceutically acceptable acid addition salt thereof.

In still another embodiment, the instant invention provides a method ofinhibiting DPP-IV comprising administering to a mammal in need of suchtreatment a therapeutically effective amount of a compound of formula Iabove, or a pharmaceutically acceptable acid addition salt thereof,preferably a compound of formula Ia above, or a pharmaceuticallyacceptable acid addition salt thereof, more preferably a compound offormula Ib above, or a pharmaceutically acceptable acid addition saltthereof, and even more preferably a compound of formula Ic above, or apharmaceutically acceptable acid addition salt thereof.

In a further embodiment, the instant invention provides a method oftreating conditions mediated by DPP-IV inhibition comprisingadministering to a mammal in need of such treatment a therapeuticallyeffective amount of a compound of formula I above, or a pharmaceuticallyacceptable acid addition salt thereof, preferably a compound of formulaIa above, or a pharmaceutically acceptable acid addition salt thereof,more preferably a compound of formula Ib above, or a pharmaceuticallyacceptable acid addition salt thereof, and even more preferably acompound of formula Ic above, or a pharmaceutically acceptable acidaddition salt thereof.

In the above definitions, it should be noted that the “alkoxy”significance is either straight or branched chain, of which examples ofthe latter are isopropyl and t-butyl.

The acid addition salts of the compounds of formula I may be those ofpharmaceutically acceptable organic or inorganic acids. Although thepreferred acid addition salts are the hydrochlorides, salts ofmethanesulfonic, sulfuric, phosphoric, citric, lactic and acetic acidmay also be utilized.

The compounds of formula I may be prepared by the following two-stepreaction scheme:

where R is as defined above.

As to the individual steps, Step 1 involves the reaction of pyrrolidineof formula II with a slight molar excess of bromoacetylbromide andtriethylamine and a catalytic amount of dimethylaminopyridine (DMAP) toobtain the bromide compound of formula III. The reaction is conducted inthe presence of an inert, organic solvent, preferably a chlorinated,aliphatic hydrocarbon such as methylene chloride, at a temperature offrom 0° to 25° C., preferably at a temperature between 0° and 15° C.,for a period of between 2 and 6 hours, preferably between 2 and 4 hours.

Step 2 concerns the reaction of the bromide compound prepared in Step 1,i.e., the bromide compound of formula III, with at least 3 equivalentsof a primary amine compound of formula IV to obtain an N-(substitutedglycyl)-pyrrolidine compound of formula I. The reaction is conducted inthe presence of an inert, organic solvent, preferably a cyclic ethersuch as tetrahydrofuran, at a temperature of from 0° to 35° C.,preferably at a temperature between 0° and 25° C., for a period ofbetween 1 and 20 hours.

The primary amine compounds of formula IV are known and may be preparedby procedures well documented in the literature. For example: a)1-hydroxymethylcyclopentylamine can be prepared by the reduction of1-amino-1-cyclopentane carboxylic acid with lithium aluminum hydride asset forth below:

The reduction is conducted in the presence of an inert, organic solvent,preferably a cyclic ether such as tetrahydrofuran, at the refluxtemperature of the solvent for a period of between 14 and 24 hours. (b)2-[(5-chloropyridin-2-yl)amino]ethylamine can be prepared by refluxing amixture of 2,5-dichloropyridine with ethylenediamine in an oil bath fora period of between 6 and 12 hours. (c) Similarly,2-[(5-trifluoromethylpyridin-2-yl)amino]ethylamine can be prepared byrefluxing a mixture of 2-chloro-5-trifluoromethyl pyridine withethylenediamine in an oil bath for a period of between 6 and 12 hours.(d) 2-[(5-cyanopyridin-2-yl)amino]ethylamine can be prepared by stirringa mixture of 2-chloropyridine-5-carbonitrile and ethylenediamine at atemperature between 20° and 30° C., for a period of between 4 and 6hours. (e) 2-[(pyrimidin-2-yl)amino]ethylamine can be prepared by addingethylenediamine to ice-bath cooled 2-chloropyrimidine and allowing themixture to react at a temperature between 20° and 30° C., for a periodof between 12 and 20 hours.

As indicated above, the compounds of formula I form pharmaceuticallyacceptable acid addition salts. For example, the free base of a compoundof formula I can be reacted with hydrochloric acid in gaseous form toform the corresponding mono- and di-hydrochloride salt forms, whereasreacting the free base with methanesulfonic acid forms the correspondingmesylate salt form. All pharmaceutically acceptable acid addition saltforms of the compounds of formula I are intended to be embraced by thescope of this invention.

As indicated above, all of the compounds of formula I, and theircorresponding pharmaceutically acceptable acid addition salts, areuseful in inhibiting DPP-IV. The ability of the compounds of formula I,and their corresponding pharmaceutically acceptable acid addition salts,to inhibit DPP-IV may be demonstrated employing the Caco-2 DPP-IV Assaywhich measures the ability of test compounds to inhibit DPP-IV activityfrom human colonic carcinoma cell extracts. The human colonic carcinomacell line Caco-2 was obtained from the American Type Culture Collection(ATCC HTB 37). Differentiation of the cells to induce DPP-IV expressionwas accomplished as described by Reisher, et al. in an article entitled“Increased expression of . . . intestinal cell line Caco-2” in Proc.Natl. Acad. Sci., Vol. 90, pgs. 5757-5761 (1993). Cell extract isprepared from cells solubilized in 10 mM Tris-HCl, 0.15 M NaCl, 0.04t.i.u. aprotinin, 0.5% nonidet-P40, pH 8.0, which is centrifuged at35,000 g for 30 min. at 4° C. to remove cell debris. The assay isconducted by adding 20 μg solubilized Caco-2 protein, diluted to a finalvolume of 125 μl in assay buffer (25 mM Tris-HCl pH 7.4, 140 mM NaCl, 10mM KCl, 1% bovine serum albumin) to microtiter plate wells. The reactionis initiated by adding 25 μl of 1 mM substrate (H-Alanine-Proline-pNA;pNA is p-nitroaniline). The reaction is run at room temperature for 10minutes after which time a 19 μl volume of 25% glacial acetic acid isadded to stop the reaction. Test compounds are typically added as 30 μladditions and the assay buffer volume is reduced to 95 μl. A standardcurve of free p-nitroaniline is generated using 0-500 μM solutions offree pNA in assay buffer. The curve generated is linear and is used forinterpolation of substrate consumption (catalytic activity in nmolessubstrate cleaved/min). The endpoint is determined by measuringabsorbance at 405 nm in a Molecular Devices UV Max microtiter platereader. The potency of the test compounds as DPP-IV inhibitors,expressed as IC₅₀, is calculated from 8-point, dose-response curvesusing a 4-parameter logistic function.

The following IC₅₀s were obtained:

Compound Caco-2 DPP-IV (μM) Ex. 1 5.5 Ex. 2A 2.6 Ex. 2B 27.5 Ex. 2C 9.7Ex. 2D 6.4 Ex. 3 3.0

The ability of the compounds of formula I, and their correspondingpharmaceutically acceptable acid addition salts, to inhibit DPP-IV mayalso be demonstrated by measuring the effects of test compounds onDPP-IV activity in human and rat plasma employing a modified version ofthe assay described by Kubota, et al. in an article entitled“Involvement of dipeptidylpeptidase IV in an in vivo immune response” inClin. Exp. Immunol., Vol. 89, pgs. 192-197 (1992). Briefly, five μl ofplasma are added to 96-well flat-bottom mictotiter plates (Falcon),followed by the addition of 5 μl of 80 mM MgCl₂ in incubation buffer (25mM HEPES, 140 mM NaCl, 1% RIA-grade BSA, pH 7.8). After a 5 min.incubation at room temperature, the reaction is initiated by theaddition of 10 μl of incubation buffer containing 0.1 mM substrate(H-Glycine-Proline-AMC; AMC is 7-amino-4-methylcoumarin). The plates arecovered with aluminum foil (or kept in the dark) and incubated at roomtemperature for 20 min. After the 20 min. reaction, fluorescence ismeasured using a CytoFluor 2350 fluorimeter (Excitation 380 nm Emission460 nm; sensitivity setting 4). Test compounds are typically added as 2μl additions and the assay buffer volume is reduced to 13 μl. Afluorescence-concentration curve of free AMC is generated using 0-50 μMsolutions of AMC in assay buffer. The curve generated is linear and isused for interpolation of substrate consumption (catalytic activity innmoles substrate cleaved/min). As with the previous assay, the potencyof the test compounds as DPP-IV inhibitors, expressed as IC₅₀, iscalculated from 8-point, dose-response curves using a 4 parameterlogistic function.

The following IC₅₀s were obtained:

Compound human plasma DPP-IV (μM) rat plasma DPP-IV (μM) Ex. 1 15.9 9.3Ex. 2A 9.2 4.4 Ex. 2B 45.8 28.4 Ex. 2C 15.2 7.8 Ex. 2D 9.4 22.9 Ex. 35.3 5.2

In view of their ability to inhibit DPP-IV, the compounds of formula I,and their corresponding pharmaceutically acceptable acid addition salts,are useful in treating conditions mediated by DPP-IV inhibition. Forexample, the compounds of formula I, and their correspondingpharmaceutically acceptable acid addition salts, improve early insulinresponse to an oral glucose challenge and, therefore, are useful intreating non-insulin-dependent diabetes mellitus. The ability of thecompounds of formula I, and their corresponding pharmaceuticallyacceptable acid addition salts, to improve early insulin response to anoral glucose challenge may be measured in insulin resistant ratsaccording to the following method:

Male Sprague-Dawley rats that had been fed a high fat diet (saturatedfat=57% calories) for 2-3 weeks were fasted for approximately 2 hours onthe day of testing, divided into groups of 8-10, and dosed orally with10 μmol/kg of the test compounds in CMC. An oral glucose bolus of 1 g/kgwas administered 30 minutes after the test compound directly into thestomach of the test animals. Blood samples, obtained at varioustimepoints from chronic jugular vein catheters were analyzed for plasmaglucose and immunoreactive insulin (IRI) concentrations, and plasmaDPP-IV activity. Plasma insulin levels were assayed by a double antibodyradioimmunoassay (RIA) method using a specific anti-rat insulin antibodyfrom Linco Research (St. Louis, Mo.). The RIA has a lower limit ofdetection of 0.5 μU/ml with intra- and inter-assay variations of lessthan 5%. Data are expressed as % increase of the mean of the controlanimals. Upon oral administration, each of the compounds testedamplified the early insulin response which led to an improvement inglucose tolerance in the insulin resistant test animals.

The precise dosage of the compounds of formula I, and theircorresponding pharmaceutically acceptable acid addition salts, to beemployed for treating conditions mediated by DPP-IV inhibition dependsupon several factors, including the host, the nature and the severity ofthe condition being treated, the mode of administration and theparticular compound employed. However, in general, conditions mediatedby DPP-IV inhibition are effectively treated when a compound of formulaI, or a corresponding pharmaceutically acceptable acid addition salt, isadministered enterally, e.g., orally, or parenterally, e.g.,intravenously, preferably orally, at a daily dosage of 0.10-100,preferably 1-75 mg/kg body weight or, for most larger primates, a dailydosage of 5-7,000, preferably 25-5,000, more preferably 50-2500 mg. Atypical dosage unit is 0.5-10 mg/kg, one to three times a day.

Usually, a small dose is administered initially and the dosage isgradually increased until the optimal dosage for the host undertreatment is determined. The upper limit of dosage is that imposed byside effects and can be determined by trial for the host being treated.

The compounds of formula I, and their corresponding pharmaceuticallyacceptable acid addition salts, may be combined with one or morepharmaceutically acceptable carriers and, optionally, one or more otherconventional pharmaceutical adjuvants and administered enterally, e.g.,orally, in the form of tablets, capsules, caplets, etc. or parenterally,e.g., intravenously, in the form of sterile injectable solutions orsuspensions. The enteral and parenteral compositions may be prepared byconventional means.

The compounds of formula I, and their corresponding pharmaceuticallyacceptable acid addition salts, may be formulated into enteral andparenteral pharmaceutical compositions containing an amount of theactive substance that is effective for treating conditions mediated byDPP-IV inhibition, such compositions in unit dosage form and suchcompositions comprising a pharmaceutically acceptable carrier.

The following examples show representative compounds encompassed by thisinvention and their synthesis. However, it should be clearly understoodthat they are for purposes of illustration only.

EXAMPLE 1

1-[2-[(5-chloropyridin-2-yl)amino]ethylamino]acetylpyrrolidine.

a) Preparation of 1-bromoacetylpyrrolidine.

25.0 g (350 mmol) of pyrrolidine, 39.0 g (387 mmol) of triethylamine and200 mg of dimethylaminopyridine (DMAP) are dissolved in 200 ml ofmethylene chloride and the solution is then added, dropwise, to anice-cold solution of 34.0 ml (387 mmol) of bromoacetylbromide in 200 mlof methylene chloride, over a period of 60 minutes under a calciumsulfate drying tube. The resulting clear, golden-brown solution is thenstirred at ice-water temperature under a calcium sulfate drying tube,after which time, it is poured into 1.5 liters of ethyl acetate. Theresulting white precipitate is filtered, washed with ethyl acetate, andthe filtrate is concentrated to obtain the desired compound as a brownoil.

b) Preparation of the title compound.

To a 200 ml. flask is added 4.7 g (27 mmol) of2-[(5-chloropyridin-2-yl)amino]ethylamine and 16 ml of tetrahydrofuranand the mixture is cooled in an ice bath. To the cooled mixture isadded, dropwise, a solution of 1.74 g (91 mmol) of the compound preparedin a) above in 10 ml of tetrahydrofuran. The resultant mixture is thenstirred for 1 hour at 0° C. under a calcium sulfate drying tube and thenallowed to stir at room temperature for 18 hours. The solvent is thenremoved by rotovaping and the resultant oily paste is partitionedbetween methylene chloride and water. The product is then extracted intothe methylene chloride layer and the aqueous layer is then washed twicewith methylene chloride. The combined organic layers are then washedsuccessively with water and brine, dried over sodium sulfate, andconcentrated to obtain the desired compound in crude form. The crudeform is then purified on silica gel employing a mixture of 5% methanolin methylene chloride as the eluent to yield the desired compound as anoff-white solid, m.p. 118°-119° C.

EXAMPLE 2

Following essentially the procedure of Example 1b), and using in placeof the amine therein, an equivalent amount of:

a) 2-[(5-cyanopyridin-2-yl)amino]ethylamine;

b) 2-[pyrimidin-2-yl)amino]ethylamine;

c) (1-hydroxymethyl)cyclopentylamine; and

d) 2-[(pyridin-2-yl)amino]ethylamine;

there is obtained:

A) 1-[2-[(5-cyanopyridin-2-yl)amino]ethylamino]acetylpyrrolidine as anoff-white solid, m.p., 122°-123° C.;

B) 1-[2-(pyrimidin-2-yl)amino]ethylamino]acetylpyrrolidine as a yellowwax which softens at 42° C.;

C) 1-[(1-hydroxymethylcyclopent-1-yl)amino]acetylpyrrolidine as a lightyellow solid, m.p., 72°-74° C.; and

D) 1-[2-[(pyridin-2-yl)amino]ethylamino]acetylpyrrolidine as a whitesolid, m.p., 98°-100° C., respectively.

EXAMPLE 3

1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidinedihydrochloride.

a) Preparation of the title compound in free base form.

Following essentially the procedure of Example 1b), and using in placeof the amine therein, an equivalent amount of2-[(5-nitropyridin-2-yl)amino]ethylamine, the desired compound isobtained as a golden yellow solid.

b) Preparation of the title compound.

After dissolving the free base compound prepared in a) above in 150 mlof dry tetrahydrofuran, hydrogen chloride gas is bubbled into thesolution for approximately 30 seconds. The off-white precipitate thatforms is then filtered, washed with dry tetrahydrofuran and the solventis removed by high vacuum pumping to obtain the title compound as a tansolid, m.p. 220°-222° C.

What is claimed is:
 1. A compound of formula I:

wherein R is a group CH₂₂NH—R₁, where R₁ is an unsubstituted pyridinering or a pyridine ring mono- or di-substituted by halo,trifluoromethyl, cyano or nitro; or a pharmaceutically acceptable acidaddition salt thereof.
 2. A compound of formula Ib:

wherein R″ is a group CH₂₂NH—R″₁, where R″₁ is a pyridine ring mono-or a di-substituted by halo, trifluoromethyl, cyano or nitro; or apharmaceutically acceptable acid addition salt thereof.
 3. A compound offormula Ic:

wherein R″′ is a group CH₂₂NH—R″′₁, where R″′₁ is a pyridine ringmonosubstituted by halo, trifluoromethyl, cyano or nitro; or apharmaceutically acceptable acid addition salt thereof.
 4. The compoundaccording to claim 3 which is1-[2-[(5-cyanopyridin-2-yl)amino]ethylamino]acetylpyrrolidine.
 5. Thecompound according to claim 3 which is1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidine, or apharmaceutically acceptable acid addition salt thereof.
 6. The compoundaccording to claim 5 which is1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidinedihydrochloride.
 7. A pharmaceutical composition comprising apharmaceutically acceptable carrier or diluent and a therapeuticallyeffective amount of a compound according to claim 1, or apharmaceutically acceptable acid addition salt thereof.
 8. Apharmaceutical composition comprising a pharmaceutically acceptablecarrier or diluent and a therapeutically effective amount of a compoundaccording to claim 2, or a pharmaceutically acceptable acid additionsalt thereof.
 9. A pharmaceutical composition comprising apharmaceutically acceptable carrier or diluent and a therapeuticallyeffective amount of a compound according to claim 3, or apharmaceutically acceptable acid addition salt thereof.
 10. Apharmaceutical composition according to claim 9 comprising atherapeutically effective amount of1-[2-[(5-cyanopyridin-2-yl)amino]ethylamino]acetylpyrrolidine.
 11. Apharmaceutical composition according to claim 9 comprising atherapeutically effective amount of1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidine, or apharmaceutically acceptable acid addition salt thereof.
 12. Apharmaceutical composition according to claim 11 comprising atherapeutically effective amount of1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidinedihydrochloride.
 13. A method of treating non-insulin-dependent diabetesmellitus comprising administering to a mammal in need of such treatmenta therapeutically effective amount of a compound according to claim 1,or a pharmaceutically acceptable acid addition salt thereof.
 14. Amethod of treating non-insulin-dependent diabetes mellitus comprisingadministering to a mammal in need of such treatment a therapeuticallyeffective amount of a compound according to claim 2, or apharmaceutically acceptable acid addition salt thereof.
 15. A method oftreating non-insulin-dependent diabetes mellitus comprisingadministering to a mammal in need of such treatment a therapeuticallyeffective amount of a compound according to claim 3, or apharmaceutically acceptable acid addition salt thereof.
 16. A methodaccording to claim 15 comprising administering a therapeuticallyeffective amount of1-[2-[(5-cyanopyridin-2-yl)amino]ethylamino]acetylpyrrolidine.
 17. Amethod according to claim 15 comprising administering a therapeuticallyeffective amount of1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidine, or apharmaceutically acceptable acid addition salt thereof.
 18. A methodaccording to claim 17 comprising administering a therapeuticallyeffective amount of1-[2-[(5-nitropyridin-2-yl)amino]ethylamino]acetylpyrrolidinedihydrochloride.